Expandable orthopedic device

ABSTRACT

A device for stabilizing bone includes a tubular body having first and second end regions defining a longitudinal axis therebetween. A plurality of splines extend from the first end region, the splines including first ends coupled to the first end region, and second ends disposed away from the first end region, the second ends being directable from a generally axial collapsed state to a substantially transverse expanded state. A plurality of support arms are coupled to the splines, and an actuator is coupled to the support arms, the actuator movable axially relative to the elongate body for causing the support arms to direct the second ends of the splines from the collapsed state to the expanded state. Optionally, the device includes another set of splines extending from the second end region or located at an intermediate region of the tubular body.

RELATED APPLICATION DATA

This application is a continuation of co-pending U.S. application Ser.No. 10/349,210, filed Jan. 21, 2003, which is a continuation of U.S.application Ser. No. 09/907,514, filed Jul. 16, 2001, now U.S. Pat. No.6,554,833, which is a continuation-in part of U.S. application Ser. No.09/426,563, filed Oct. 22, 1999, now U.S. Pat. No. 6,261,289 on Jul. 17,2001, which claims benefit of U.S. Provisional Application Ser. No.60/105,593 filed Oct. 26, 1998, and of PCT Application Serial No.PCT/IL00/00666, filed Oct. 19, 2000 and published on Apr. 26, 2001 as WO01/28443, the disclosures of which are expressly incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to orthopedic devices for surgicaltreatment of bone fractures and for the prophylactic treatment ofpathological bones, and more particularly to expandable intramedullarydevices, and to methods for making and using such devices.

BACKGROUND OF THE INVENTION

Fractures of limb bones have been treated with internal fixationdevices, such as plates lying on the surface of a bone, nails runninginside the medullary canal of a fractured bone, and/or screws affixingboth ends of a fractured bone together. These internal fixation devicesmay provide reasonable structural rigidity and/or stability to thefractured bone without compromising some of the strain desired tostimulate bone cells.

An intramedullary fixation method is a traditional procedure fortreating long bone fractures, affixing the bone fracture usingintramedullary nails, without disturbing the periosteum of the bone.Such a method may be accomplished in a closed manner, and the fracturedbone may be functionally used (including weight bearing) during healing.The surgical approach for insertion of intramedullary nails variesslightly for each bone and is well described in the orthopedicliterature.

Some of the problems associated with conventional intramedullaryfixation methods include lack of rotation stability, collapse of thefracture site in some fracture types, and/or undesired backup of nails.Furthermore, although the actual shape of the bone typically includessome degree of curvature, the intramedullary nails used to mend thefractured bone are generally straight. Still further, intramedullaryfixation methods may introduce interlocking screws across the nail,creating some disadvantages. Specifically, conventional intramedullaryfixation nails for long bones may include a rigid structure (hollow orfull), that may be locked at their extremes by the addition of screwstransversally applied through the bone walls and the nail itself. Thisadditional step generally makes the operation longer and morecomplicated, and may require additional skin incisions and/or longer useof an image intensifier (X-ray). Furthermore, undesired gaps between thebone ends may originate from the screws, which are permanent unlessremoved in a new operation. Also, the resultant structure in certainsituations may be too stiff and may lack desired elasticity. Incontaminated fractures, metallic intramedullary nails may propagatecontamination through the entire canal, despite attempts at cleaning thefracture site, which may lead to bone infection.

Recent developments in the intramedullary fixation approach haveattempted to address some of these problems. For example, PCTPublication No. WO 98/38918 to Beyar suggests three structural designs:(1) a solid metal sheet that expands in the medullary canal; (2) ameshwork structure consisting of ribs circumferentially connected at thetips; and (3) a balloon structure that is inflated once inserted intothe medullary canal. The first two structures, however, may not providefirm support within the metaphysis of the bone. Specifically, thesestructures are unable to expand at their ends, because the totalexpansion of the structures is limited by the circumference of thediaphyseal segment of the medullary canal. The balloon structure alsohas limited utility because, when inflated, it may disrupt blood supplyof the bone and prevent regeneration or recovery, and/or may not beadjustable to changes in the shape of the medullary canal, because ofits set volume once inserted and inflated.

U.S. Pat. No. 5,281,225 to Vicenzi discloses a structure that includes amultitude of elastically deformable stems connected together by a stub.When inserted in the medullary canal of a fractured bone, the distaltips of the stems expand outward into the end of the medullary canal toanchor the Vicenzi structure within the bone. This device, however, is apassive device, expanding automatically upon deployment, and may not becontrollably expanded. Additionally, the Vicenzi structure is notexpanded within the medullary canal and, thus, does not provide multiplepoints of contact with the wall of the medullary canal. As a result, theVicenzi structure may not ensure structural stability along thetransversal and rotational planes of the fractured bone.

Accordingly, intramedullary devices that provide and/or ensure stabilityto a fractured bone would be considered useful.

SUMMARY OF THE INVENTION

The present invention is directed to orthopedic devices for surgicaltreatment of bone fractures and for the prophylactic treatment ofpathological bones, and more particularly to expandable intramedullarydevices, and to methods for manufacturing and implanting them.

According to a first aspect of the present invention, a device forstabilizing bone includes an elongate body having first and second endregions defining a longitudinal axis therebetween. A plurality ofsplines extend from the first end region, the splines including firstends coupled to the first end region of the elongate body, and secondends disposed away from the first end region, the second ends of thesplines being directable from a generally axial collapsed state to asubstantially transverse expanded state. Support arms are coupled to thesplines, and an actuator is coupled to the support arms, the actuatormovable axially relative to the elongate body for causing the supportarms to direct the second ends of the splines from the collapsed stateto the expanded state.

In one embodiment, the elongate body is a tubular shaft including alumen extending between the proximal and distal end regions, and theactuator includes an elongate member received within the lumen, andpreferably slidably coupled to the tubular shaft by mating threadedregions. A collar is coupled to the elongate member and to the supportarms. Preferably, the elongate member includes a threaded region overwhich the collar is threaded such that rotation of the elongate memberrelative to the tubular shaft causes the collar to move axially, therebycausing the support arms to direct the splines between the collapsed andexpanded states.

In accordance with another aspect of the present invention, a device forstabilizing bone includes an elongate body having first and second endregions defining a longitudinal axis therebetween, and an intermediateregion between the first and second end regions. A first plurality ofsplines extend from the first end region, the splines being directablefrom a generally axial collapsed state to a substantially transverseexpanded state. A second plurality of splines extend from a region ofthe elongate body distal to the proximal end region, the splines beingdirectable from a generally axial collapsed state to a substantiallytransverse expanded state.

First and second pluralities of support arms are coupled to the firstand second plurality of splines, respectively, and an actuator iscoupled to the support arms. The actuator is movable axially relative tothe elongate body for causing the first and second pluralities ofsupport arms to direct the splines between the collapsed and expandedstates.

Preferably, the elongate body is a tubular shaft including a lumenextending between the proximal and distal end regions, and the actuatorincludes an elongate member received within the lumen. First and secondcollars are coupled to the elongate member and to the first and secondpluralities of support arms, respectively. Rotation of the elongatemember relative to the tubular shaft causes the first and second collarsto move axially, thereby causing the first and second pluralities ofsupport arms to direct the splines between the collapsed and expandedstates.

In one embodiment, the second plurality of splines extend distally fromthe distal end region of the tubular shaft. The elongate member mayinclude first and second threaded regions having thread patterns thatare opposite hand relative to one another. The first and second collarsare threadably coupled to the first and second threaded regions,respectively. Because of the opposite hand thread arrangement, rotationof the elongate member may cause the collars to move in oppositedirections. Thus, rotating the elongate member in a first direction maycause the collars to move away from one another to expand the splines,while rotating the elongate member in the opposite direction may causethe collars to move towards one another and collapse the splines.

In an alternative embodiment, the second plurality of splines may belocated on the intermediate region of the tubular shaft. In a furtheralternative, additional sets of splines may be located along the tubularshaft in addition to those described above. Thus, a single actuator maybe used to expand multiple sets of splines on a single device. Thesplines may have differing shapes and/or lengths, thereby enabling thedevice to be implanted within a bone cavity having a predeterminedshape.

Optionally, an axial extension may be provided in a device in accordancewith the present invention, e.g., extending proximally from the proximalend of the device beyond the splines. For example, the elongate membermay be extended proximally beyond the splines on the first end of thetubular shaft, or the tubular shaft itself may include an extension.Holes may be provided in the axial extension through which nails,screws, or other fixation elements may be received to provide additionaltransverse support. In a further option, an indicator element may extendproximally from the device or the elongate member may be extended tofacilitate location of the device after implantation.

In accordance with yet another aspect of the present invention, a methodis provided for making a device for stabilizing bone. An elongatetubular shaft is provided including first and second end regionsdefining a longitudinal axis therebetween. Splines are formed havingfirst ends remaining attached to the first end region of the tubularbody and second ends disposed axially relative to the first ends, thesecond ends being freely movable relative to the tubular body.Preferably, the splines are formed by creating longitudinal slots in thefirst end region. Support arms are formed in the splines, the supportarms having first ends that are freely movable relative to the splinesand second ends remaining attached to the splines. Preferably, thesupport arms are formed by partially cutting away portions of respectivesplines.

The first ends of the support arms may be coupled to an actuator, andthe actuator may be movable axially relative to the tubular shaft forbuckling the support arms transversely outward relative to thelongitudinal axis, thereby directing the second ends of the splinestransversely outward. In a preferred embodiment, the actuator includesan elongate member and a first collar. The elongate member may beinserted into an axial lumen in the tubular shaft, and the first collarmay be threaded over the elongate member until the collar is proximatethe first ends of the support arms. The first ends of the support armsmay then be coupled to the first collar.

In a preferred embodiment, the tubular shaft includes an internalthreaded portion within the lumen, and the elongate member also includesa mating threaded region that slidably engages the threaded portion ofthe tubular shaft. Thus, axial movement of the elongate member relativeto the tubular shaft may be limited except upon controlled rotation ofthe elongate member.

Optionally, a second set (or additional sets) of splines and supportarms may be formed on other regions of the tubular shaft, e.g., on oneof the second end region or an intermediate region of the tubular shaft.In this case, a second collar may be threaded over the elongate memberuntil the second collar is proximate the second set of support arms, andthe second set of support arms coupled to the second collar.

A device in accordance with the present invention may be insertedthrough an entry portal previously formed using conventional procedures,e.g., into a medullary canal of a bone, such as the femur, with thesplines collapsed. Preferably, a guidewire is first introduced throughthe entry portal into the medullary canal of the bone using conventionalmethods and extended to a distal segment of the bone. The device maythen be advanced over the guidewire into the medullary canal. Afterinsertion of the device, the guidewire may be removed.

Once the device is fully inserted within the medullary canal, theactuator may be activated, e.g., using a tool inserted into the entryportal, to expand the splines to the expanded state such that thesplines substantially engage internal bone or other tissue, therebysubstantially anchoring the device relative to the bone. Thus, thedevice may prevent segments of a fractured bone within which the deviceis implanted from moving axially, bending, and/or rotating relative toone another. Optionally, if additional stability is desired, anextension may be provided that extends beyond the splines, and fixationdevices, e.g., screws or nails, may be introduced transversely into thebone, and through holes in the extension to further secure the segmentsof bone.

After the fracture has healed, the device may be removed usingconventional access procedures. During such removal, a tool may beintroduced to activate the actuator and direct the splines back to thecollapsed state before removal from the bone.

Other objects and features of the present invention will become apparentfrom consideration of the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1-3 are sectional side views of a femur, a tibia, and a humerus,respectively.

FIGS. 4A and 4B are perspective views of a first embodiment of anintramedullary device in accordance with the present invention, withsplines in collapsed and expanded states, respectively.

FIGS. 5A and 5B are perspective views of one end of the device of FIGS.4A and 4B, showing splines on the end in collapsed and expanded states,respectively.

FIGS. 6A and 6B are cross-sectional views of a femur including afracture being stabilized by the device of FIGS. 4A and 4B.

FIGS. 7A and 7B are perspective views of a second embodiment of anintramedullary device in accordance with the present invention, withsplines in collapsed and expanded states, respectively.

FIGS. 8A and 8B are perspective views of one end of the device of FIGS.7A and 7B, showing splines on the end in collapsed and expanded states,respectively.

FIGS. 9A and 9B are cross-sectional views of a femur including afracture being stabilized by a third embodiment of an intramedullarydevice, in accordance with the present invention.

FIGS. 10A, 10B, 11A, and 11B are cross-sectional views of a femurincluding a fracture being stabilized by alternative embodiments ofintramedullary devices, in accordance with the present invention.

FIG. 12 is a perspective view of a fourth preferred embodiment of anintramedullary device in accordance with the present invention, withsplines in an expanded state.

FIGS. 13A and 13B are perspective views of one end of the device of FIG.12, showing the splines in a collapsed state and the expanded state,respectively.

FIGS. 14A and 14B are cross-sectional side views of the device of FIGS.12 and 13, showing the splines in collapsed and expanded states,respectively.

FIGS. 15A-15D are perspective views, showing a method for formingsplines in a tubular body, in accordance with the present invention.

FIG. 16 is a perspective view of an alternative embodiment of anintramedullary device, in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention may be employed to mend a variety of fracturedbones, such as the femur, tibia, or humerus. By way of background thepertinent features of these bones will be described with reference toFIGS. 1-3. Referring specifically to FIG. 1, a femur 100 may be dividedinto six anatomical regions: a diaphysis or midshaft 102, proximalmetaphysis 104, distal metaphysis 106, proximal epiphysis or head 108,distal epiphysis 110, and femoral neck 112. The femur 100 is composed ofa hard cortex 114 and a medullary cavity 116. For the purposes of thisinvention, the medullary cavity 116, includes a medullary canal 118,which runs through the center of the shaft 102, as well as proximal anddistal metaphyseal areas 120 and 122, and proximal and distal epiphysealareas 124 and 126.

Referring specifically to FIG. 2, a tibia 140 may be divided into fiveanatomical regions: a diaphysis or midshaft 142, a proximal metaphysis144, distal metaphysis 146, proximal epiphysis 148, and distal epiphysis150. Like the femur 100, the tibia 140 is composed of a hard cortex 152and a medullary cavity 154. For the purposes of this specification, amedullary cavity 154 includes a medullary canal 156, which runs throughthe center of the shaft 142, as well as proximal and distal metaphysealareas 158 and 160, and proximal and distal epiphyseal areas 162 and 164.

Referring to FIG. 3, a humerus 170, like the tibia 140, may be dividedinto five anatomical regions: a diaphysis or midshaft 172, proximalmetaphysis or neck 174, distal metaphysis 176, proximal epiphysis orhead 178, and distal epiphysis 180. Like the femur 100 and tibia 140,the humerus 170 is composed of a hard cortex 182 and a medullary cavity184. For the purposes of this specification, a medullary cavity 184includes a medullary canal 186, which runs through the center of theshaft 172, as well as proximal and distal metaphyseal areas 188 and 190,and proximal and distal epiphyseal areas 192 and 194.

It should be emphasized that the femur 100, tibia 140, and humerus 170represent exemplary bones in which devices of the present invention maybe employed. The present invention maybe used to mend fractured bones,other than the femur 100, tibia 140, and humerus 170, without strayingfrom the scope of the present invention.

Although the medullary canals of the femur 100, tibia 140, and humerus170 have a generally uniform circumference along the shafts of thesebones, the medullary canals are in communication with larger metaphysealand epiphyseal areas. Thus, the medullary cavities of the femur 100,tibia 140, and humerus 170, as a whole, have a differentialcircumference, with the circumference at the ends being greater than thecircumference at the middle of these medullary cavities. Theintramedullary devices of the present invention may be reversiblyexpanded, e.g., to adopt a pre-formatted shape, fitting the internalshape of the medullary cavity. Use of the intramedullary devices of thepresent invention may rotationally lock the bone segments of a fracturedbone, while at the same time providing sufficient stability in the otherplanes without the necessity of screws. If screws are needed, they maybe used in conjunction with the intramedullary devices. These devicesare minimally invasive, and may be implanted through a single incision,the entry portal. Different lengths and types of the intramedullarydevices may be necessary, depending upon the bone to be fixed. Theintramedullary devices may accommodate a variety of bone circumferences.

The intramedullary devices may be deployed using methods similar tothose used for conventional intramedullary nails for bones, such as thefemur, tibia and humerus, while minimizing the X-rays needed after theclose reduction of the fracture and control of insertion. Theintramedullary devices may also be deployed in the radius and ulnathrough standard approaches used for the insertion of Rush-type nails.For immature bones (with open physis), the intramedullary devices may beinserted through entry portals below the proximal physis and above thedistal physis, without including them in the area of fixation. A longintramedullary device may be used, for instance, in knee fusion casesincluding the femur and tibia. A short intramedullary device may beused, for instance, with metatarsal and metacarpal bone fractures.

This intramedullary approach, along with the minimally invasive natureof the intramedullary devices, generally leaves the periosteum of thefractured bone untouched. In addition, the intramedullary devices may belighter without compromising the stability, allow better visualizationon follow up X-rays due to less metal, and are compatible with the useof other types of externally biomechanic stimuli that could bepotentially used as union enhancement treatment. Using certain alloys,the material in which the intramedullary devices are constructed frommay remain non-magnetic, avoiding interference with most modern imagingtechniques, such as MRI (magnetic resonance imaging).

Turning to FIGS. 4 and 5, a first preferred embodiment of anintramedullary device 200 is shown that includes a tubular shaft 202,and proximal and distal ends 204, 206 defining a longitudinal axis 208therebetween. The tubular shaft 202 is a generally tubular body, e.g.,having a circular or other cross-section. The tubular body may have asolid wall or may have a lattice or other pattern of holes (not shown)formed therein, e.g., for facilitating fluid flow therethrough, forminimizing weight, for providing a desired flexibility, and/or forallowing expansion of the tubular shaft 202. In an alternativeembodiment, the tubular shaft 202 may include a plurality of axial spineelements interconnected by a mesh or other interconnecting structure,similar to the embodiments shown and described in application Ser. No.09/426,563, incorporated by reference herein.

A plurality of splines 210 extend from the proximal end 204 andpreferably from both the proximal and the distal ends 204, 206 of thetubular shaft 202, as shown. The splines 210 are expandable between agenerally axial collapsed state (shown in FIGS. 4A and 5A) and asubstantially transverse expanded state (shown in FIGS. 4B and 5B). Thesplines 210 may be substantially flat bands, as shown, round wires,filaments, or other structures capable of assuming the collapsed andexpanded states.

As best seen in FIGS. 5A and 5B, each of the splines 210 includes afirst end region 210 a coupled to the tubular shaft 202 and a second endregion 210 b coupled to a collar 212. The end regions 210 a, 210 b ofthe splines 210 may be connected to the tubular shaft 202 and collar212, for example, by hinged joints (not shown). Alternatively, the endregions 210 a, 210 b may be integrally formed with the tubular shaft 202and/or collar 212, and may be sufficiently flexible to bend as needed toaccommodate movement between the collapsed and expanded states. Thus,for example, the tubular shaft 202, splines 210, and collars 212 may beformed from a single section of tubing with appropriate material removedusing conventional methods to form the splines 210, as will beappreciated by those skilled in the art.

Each spline 210 also includes an intermediate region or loop 210 c thatmay be directed substantially transversely outward with respect to thelongitudinal axis 208 to define the expanded state. In the collapsedstate, best seen in FIG. 5A, the first and second end regions 210 a, 210b of the splines 210 are generally disposed adjacent one another andextend substantially parallel to the longitudinal axis 208. The collar212 preferably has a diameter substantially smaller than a diameter ofthe tubular shaft 202 such that the collar 212 may be disposed withinthe splines 210 in the collapsed state. Thus, the intermediate regions210 c are generally coextensive with the cross-section of the tubularshaft 202 in the collapsed state.

In the expanded state, best seen in FIG. 5B, the collar 212 is displacedaxially, i.e., away from the tubular shaft 202. This action displacesthe second end regions 210 b, thereby causing the intermediate regions210 c of the splines 210 to move substantially transversely outward.Thus, in the expanded state, the splines 210 define a diameter that issubstantially greater than the diameter of the tubular shaft 202.

In an alternative embodiment, shown in FIGS. 6A and 6B, the splines 210′may include first and second end regions 210 a′, 210 b′ and intermediateregions 210 c′ that are substantially linear in the collapsed state(FIG. 6A). The first end regions 210 a′ are coupled to the tubular shaft202 and the second end regions 210 b′ are coupled to a collar 212. Thecollar 212 may be displaced axially, i.e., towards the tubular shaft202, thereby causing the intermediate regions 210 c′ to buckle and movesubstantially transversely outward until they achieve the expanded state(FIG. 6B). The splines 210′ may include scored or thinned regions (notshown) to provide hinges or otherwise ensure that the splines buckle ina predetermined manner, i.e., such that the intermediate regions 210 c′move substantially transversely outward.

To cause controlled movement of the collar 212, and consequentlyselective expansion and collapse of the splines 210, the collar 212 isconnected to an actuator (not shown). The actuator is generally disposedwithin the tubular shaft 202, and in a preferred embodiment, theactuator includes an elongate control member 214 (partially seen in FIG.6B) and an actuating collar (not shown) disposed within the shaft 202.The control member 214 may be a solid rod or tubular member having anouter end 216 coupled to the collar 212 and an inner end (not shown)within the tubular shaft 202. The inner end may have a threaded regionfor cooperating with a mating threaded region on an actuating collar(not shown). As the actuating collar is rotated within the tubular shaft202, the control member 214 is displaced axially within the tubularshaft 202, thereby displacing the collar 212 coupled to the splines 210.Thus, the actuator, via the collar 212, is coupled to the splines 210for selectively expanding the splines 210 between the collapsed andexpanded states.

Alternatively, the actuator may be a control wire (not shown) that iscoupled to the collar 212 and may be pulled, e.g., axially within thetubular shaft 202, to displace the collar 212. In this alternative, thesplines 210 may be biased to one of the collapsed and expanded states,which may be overcome by pulling the control wire, e.g., using a toolinserted into the tubular shaft 202. Other variations may be providedfor the actuator, such as mechanical, hydraulic, or pneumatic actuators,as will be appreciated by those skilled in the art.

Turning to FIGS. 6A and 6B, the device 200 may be deployed within amedullary canal 118 of a fractured femur 100, e.g., having a compoundfracture 128. Alternatively, the device 200 may be deployed in bonesother than the femur 100, such as those described above. First, thedevice 200 may be inserted through a previously formed entry portal 130into the medullary canal 118 with the splines 210 collapsed, as shown inFIG. 6A. If the control member 214 is tubular, a guidewire or otherelongate element (not shown) may first be introduced within themedullary canal 118, and the device 200 may be advanced over theguidewire, i.e., through a lumen (not shown) of the control member 214,to facilitate positioning of the device 200.

Once the device 200 is fully inserted within the medullary canal 118,the guidewire (if used) may be removed, and a tool (not shown) may bedirected through the entry portal 130 and into the tubular shaft 202 toengage and activate the actuator within the device 200. For example, thetool may be a drive tool having a rotating head that engages theactuating collar. The drive tool may be manually, pneumatically, and/orelectrically driven to rotate the actuating collar, thereby moving thecontrol member 214 axially within the tubular shaft 202, andconsequently displacing the collar 212 until the splines 210 on theproximal end 204 are expanded. The expanded splines 210 may besufficiently flexible and/or resilient to adapt to the proximalmetaphyseal area 120. Thus, the splines 210 may firmly engage the wallsof the proximal metaphyseal area 120 at a multitude of contact points.This may secure the device 200, and consequently the segments of thefractured bone both axially and/or torsionally with respect to oneanother.

Preferably, the splines 210 on the distal end 206 are simultaneouslyexpanded when the splines 210 on the proximal end 204 are expanded.Alternatively, the splines 210 on the distal end 206 may beindependently expanded by a separate actuator, e.g., using a similartool and method to that described with respect to the proximal end 204.In a further alternative, an intramedullary device may be provided thatincludes only a single set of splines, similar to the embodiments shownin FIGS. 10A-11B.

In a further alternative, if desired, the collar 212 adjacent theproximal set of splines 210 may extend further proximally from thesplines 210 and one or more holes (not shown) may be provided therein.Screws, nails, or other fixation devices (also not shown) may beinserted transversely through the bone and through these holes, in orderto further enhance the stability of the device 200. Similarly, thecollar 212 adjacent the distal set of splines 210 may extend distallyfrom the splines 210 and may include one or more holes for receivingother fixation devices therethrough, in addition to or instead of thoseon the proximal collar 212.

After the fracture has healed, the device 200 may be removed through theentry portal 130. The entry portal 130 may be covered by new bone growth(not shown) may be exposed through a small skin incision. Optionally,the device 200 may include an indicator element (not shown) that mayextend from the proximal end 204. If so, the indicator element may beprotruding from or buried under the surface of the new both growth. Thenew bone growth may be removed around the indicator element to exposethe entry portal 130. Once located, the device 200 may be collapsed byrotating the actuating collar in a direction opposite to that used toexpand the spine elements 210. The device 200 may then be withdrawn fromthe medullary canal 118, and the entry portal 130 and overlying tissueallowed to heal.

Alternatively, it may be possible to form the device 200 completely orpartially from a bioabsorbable material, so that, in some instances, asecond operation to retrieve the device 200 may not be necessary, oronly a portion of the device 200 may have to be retrieved.

Turning to FIGS. 7 and 8, a second embodiment of an intramedullarydevice 300 is shown that includes a tubular shaft 302, and proximal anddistal ends 304, 306 defining a longitudinal axis 308 therebetween. Thetubular shaft 302 is a generally tubular body, e.g., having a circularor other cross-section, similar to the tubular shaft 210 of the device200 described above.

A plurality of splines 310 extend from the proximal end 304 andpreferably from both the proximal and the distal ends 304, 306 of thetubular shaft 302, as shown. The splines 310 are expandable between agenerally axial collapsed state (shown in FIGS. 7A and 8A) and asubstantially transverse expanded state (shown in FIGS. 7B and 8B). Thesplines 310 may be substantially flat bands, filaments, or otherstructures capable of assuming the collapsed and expanded states.

As best seen in FIGS. 7A and 7B, each of the splines 310 includes afirst end region 310 a coupled to the tubular shaft 302 and a second endregion 310 b that enters the first end region 310 a of the tubular shaft302. The second end regions 310 b of the splines 310 are coupled to anactuator within the tubular shaft 302. The first end regions 310 a ofthe splines 310 may be connected to the tubular shaft 302, for example,by hinged joints (not shown), or alternatively may be integrally formedwith the tubular shaft 302, similar to the embodiments described above.

Each spline 310 also includes an intermediate region or loop 310 c thatmay be directed substantially transversely outward with respect to thelongitudinal axis 308 to define the expanded state. In the collapsedstate, best seen in FIG. 8A, the first and second end regions 310 a, 310b of the splines 310 are generally disposed adjacent one another andextend substantially parallel to the longitudinal axis 308, e.g., suchthat the intermediate regions 310 c are generally coextensive with thecross-section of the tubular shaft 302. In the expanded state, best seenin FIG. 8B, the intermediate regions 310 c of the splines 310 aredisposed substantially transversely outward. Thus, in the expandedstate, the splines 310 define a diameter that is substantially greaterthan the diameter of the tubular shaft 302.

To cause controlled expansion and collapse of the splines 310, anactuator (not shown) is generally disposed within the tubular shaft 302.In a preferred embodiment, the actuator may include a collar (not shown)slidable within the tubular shaft 302 to which the second end regions310 b are connected. The collar may be controllably displaced axiallywithin the tubular shaft 302, e.g., using a threaded collar and/or rodarrangement similar to that described above. Thus, the actuator iscoupled to the splines 310 for selectively expanding the splines 310between the collapsed and expanded states.

In one embodiment, the splines 310 may be biased to assume theirexpanded states, and the collar may be displaced axially, e.g., awayfrom the splines 310 to pull the second end regions 310 b and collapsethe splines 310 to their collapsed states. When the collar is movedaxially in the opposite direction, e.g., towards the splines 310, thesplines 310 may be free to expand to the expanded state.

During use, the device 300 may be deployed within a medullary canal of afractured bone (not shown), similar to the embodiment described above.The device 300 may be inserted through a previously formed entry portalinto the medullary canal with the splines 310 collapsed. Once the device300 is fully inserted within the medullary canal, a tool (not shown) maybe directed through the entry portal and into the tubular shaft 302 toengage and activate the actuator within the device 300, i.e., to expandthe splines 310 on the proximal end 304 to their expanded states. Theexpanded splines 310 may be sufficiently flexible and/or resilient toadapt to the proximal metaphyseal area and/or to substantially firmlyengage the walls of the proximal metaphyseal area at a multitude ofcontact points.

In one embodiment, the splines 310 on the distal end 306 may besimultaneously expanded when the splines 310 on the proximal end 304 areexpanded. Alternatively, the splines 310 on the distal end 306 may beindependently expanded by a separate actuator, e.g., using a similartool and method to that described with respect to the proximal end 304.In a further alternative, an intramedullary device may be provided thatincludes only a single set of splines, similar to the embodiments shownin FIGS. 10A-11B.

After the fracture has healed, the device 300 may be removed, similar tothe embodiment described above. During such removal, a tool is generallyintroduced into the tubular shaft 302 to engage the actuator andcollapse the splines 310, similar to the method for expanding thesplines 310. In further alternatives, the device 300 may include anindicator element (not shown) to facilitate removal of the device 300,and/or the device 300 may be at least partially composed of abioabsorbable material, similar to the embodiment described above.

Turning to FIGS. 9A and 9B, another embodiment of an intramedullarydevice 400 is shown that includes a tubular shaft 402, and proximal anddistal ends 404, 406 defining a longitudinal axis 408 therebetween,similar to the embodiments described above. A plurality of splines 410extend from the proximal end 404 and preferably from both the proximaland the distal ends 404, 406 of the tubular shaft 402, as shown. Thesplines 410 are expandable between a generally axial collapsed state(not shown) and a substantially transverse expanded state (shown in FIG.9B). The splines 410 may be substantially flat bands, filaments, orother structures having a first end 410 a connected to the tubular shaft402 and a loose end 410 b. Preferably, the splines 410 are biased toassume the expanded state but may be restrained in the collapsed stateby overlying sleeves 412, that operates similar to the slidable collarsdescribed above.

During use, the device 400 may be deployed within a medullary canal 118of a fractured femur 100, e.g., having a compound fracture 128.Alternatively, the device 400 may be deployed in bones other than thefemur 100, similar to the embodiments described above. The device 400may be inserted through a previously formed entry portal 130 into themedullary canal 118 with the splines 410 collapsed, as shown in FIG. 9A.Once the device 400 is fully inserted within the medullary canal 118,the sleeves 412 may be directed axially to expose and release thesplines 410. Preferably, the splines 210 automatically expand towardsthe expanded state, and are sufficiently flexible and/or resilient toadapt to the proximal metaphyseal area 120 and/or firmly engage thewalls of the proximal metaphyseal area 120.

After the fracture has healed, the device 400 may be removed, similar tothe embodiments described above. During such removal, a tool may beintroduced to direct the sleeves 412 back over the splines 410, similarto the method for expanding the splines 410. In further alternatives,the device 400 may include an indicator element (not shown) tofacilitate removal of the device 400.

Any of the devices described herein may be at least partially composedof a bioabsorbable material, a shape memory alloy or polymer, e.g.,Nitinol, or other resilient materials, such as stainless steel or atitanium alloy. In addition, similar to the embodiments shown in FIGS.10A to 11B, an intramedullary device may include a single set of splinesthat may be used to stabilize a bone fracture, for example, in oradjacent to a neck or other ends of a bone, such as a femur or humerus,or in a hip bone.

Turning now to FIGS. 12-14B, yet another preferred embodiment is shownof an intramedullary device 500, in accordance with the presentinvention. Generally, the device 500 includes a tubular shaft 502, oneor more collars 512, and an elongate control member 522. The tubularshaft 502 includes proximal and distal ends 504, 506 defining alongitudinal axis 508 therebetween. The tubular shaft 502 is a generallytubular body, e.g., having a circular or other cross-section (e.g.,oval, square, fluted, and the like), and defining a lumen 507 extendingbetween the proximal and distal ends 504, 506. The tubular body 508 mayhave a solid wall or may have a lattice or other pattern of holes (notshown) formed therein, e.g., for facilitating fluid flow therethrough,for minimizing weight, for providing a desired flexibility, and/or forallowing expansion of the tubular shaft 502. In an alternativeembodiment, the tubular shaft 502 may include a plurality of axial spineelements interconnected by a mesh or other interconnecting structure, asdescribed in application Ser. No. 09/426,563, incorporated above byreference.

A plurality of splines 510 extend from the proximal end 504 andpreferably from both the proximal and the distal ends 504, 506 of thetubular shaft 502, as shown. A plurality of support arms 520 are coupledto the splines 510 for expanding the splines 510 between a generallyaxial collapsed state (shown in FIGS. 13A and 14A) and a substantiallytransverse expanded state (shown in FIGS. 13B and 14B). Preferably, thesplines 510 and support arms 520 are formed from a single band ofmaterial, as explained further below. Alternatively, they may be formedas separate components that are attached to one another, e.g., bywelding, bonding, adhering, and the like. In further alternatives, thesplines 510 and/or support arms 520 may be substantially round wires,filaments, or other structures capable of assuming the collapsed andexpanded states.

As best seen in FIGS. 13A-14B, each of the splines 510 includes a firstend region 510 a coupled to the tubular shaft 502 and a second free endregion 510 c located away from the tubular shaft 502. Preferably, thesecond end region 510 c is located substantially axially away from thetubular shaft 502 in the collapsed state. Each respective support arm520 includes a first end 520 a that is coupled to collar 512 and asecond end 520 c that is coupled to a respective spline 510. Preferably,the second end 520 c of the support arm 520 is coupled to the free endregion 510 c of the spline 510, although alternatively, the second endof the support arm 520 may be coupled to an intermediate region 510 b ofthe spline 510 (not shown).

Preferably, the first end regions 510 a of the splines 510 areintegrally formed with the tubular shaft 502, while the second ends 520c of the support arms 520 are integrally formed with the second endregions 510 a of respective splines 510. The intermediate regions 510 b,520 b of the splines 510 and support arms 520 may be sufficientlyflexible to bend as needed to accommodate movement between the collapsedand expanded states, as described further below. For example, thetubular shaft 502, splines 510, and support arms 520 may be formed froma single section of tubing with appropriate material removed, asexplained further below. Alternatively, the first end regions 510 a ofthe splines 510 may be separate bands connected to the tubular shaft 502by welded joints, hinges, or pins (not shown), and/or the second ends520 c of the support arms 520 may be connected to the second end regions510 c of the splines 510 by welded joints, hinges, or pins (not shown).

Turning to FIGS. 14A and 14B, the control member 522 may be a solid rodor a tubular member having proximal and distal ends 524, 526. Thecontrol member 522 has a diameter or other cross-section such that thecontrol member 522 may be received within the lumen 507 of the tubularshaft 502. Preferably, the control member 522 includes one or morethreaded regions, such as a proximal threaded region 528 a, intermediatethreaded region 528 b, and distal threaded region 528 c, as shown. Morepreferably, the proximal and distal threaded regions 528 a, 528 c haveopposite hand threads from one another, which is explained furtherbelow.

The tubular shaft 502 may include an internal annular region 530disposed within the lumen 507 that defines an inner surface 532 that isthreaded similar to the intermediate threaded region 528 b of the rod522. The annular region 530 preferably has a diameter similar to thecontrol member 522 such that threads on the inner surface 532 engage thethreaded intermediate region 528 b to prevent axial movement of the rod522, except when the rod 522 is rotated about axis 508. The annularregion 530 may be machined from the tubular shaft 502 or may be anannular sleeve that is inserted into the lumen 507 and secured at anintermediate location, e.g., by welding, bonding, and the like.

Similarly, the collars 512 also have threaded inner surfaces that mayengage the proximal and distal threaded regions 528 a, 528 c of thecontrol member 522. Preferably, the proximal collar 512 a has aninternal threaded pattern that is opposite hand to the distal collar 512b for mating with the proximal and distal threaded regions 528 a, 528 b,respectively. In addition, the collars 512 have an outer diameter suchthat the collars 512 may be slidably received within the lumen 507 inthe proximal and distal ends 504, 506 of the tubular shaft 502. Thecollars 512 may include slots or pockets (not shown) for receiving thefirst ends 520 a of the support arms 520, as described further below.

With reference to FIGS. 15A-15D, a preferred method is shown formanufacturing the splines 510 and support arms 520 as integral elementsof the tubular shaft 502. Although only one end is shown, it will beappreciated that splines 510 and support arms 520 may be formed on bothends, if desired, as described herein. In addition, it will beappreciated that the sequence of the steps to manufacture the tubularshaft 502 is not important and may be completed in any order.

First, as shown in FIG. 15A, an elongate tube 600 is provided,preferably having a cylindrical (or other) shape, that is cut to alength (not shown) corresponding to a combined length of the finishedtubular shaft 502 and the splines 510 on one end (or both ends) of thetubular shaft 502. The tube may be formed from a variety ofbiocompatible materials that provided sufficient structural integrity,with stainless steel or titanium being preferred. First slots 602 may becreated in the end(s) 604 of the tube 600 that extend longitudinallysubstantially parallel to axis 606, thereby defining the splines 510between adjacent slots 602, as shown in FIG. 15B. The first slots 602may be formed by laser cutting, mechanical cutting, and the like. Ifdesired, the longitudinal edges defined by the first slots 602 may berounded, trimmed, or otherwise modified to prevent adjacent splines 510from catching on one another, e.g., when directed from or back to thecollapsed state.

Turning to FIG. 15C, pairs of second slots 608 may be created betweenadjacent first slots 602 that extend substantially parallel to axis 606without extending entirely to the end 601 of the tube 600. Ends of thesecond slots 608 may be connected with circumferential slots 610,thereby defining support arms 520. Thus, each of the splines 520 may bedefined by a pair of narrow stems 511 that extend on either side of arespective support arm 520 from the tubular shaft 502 and terminate in afree end 510 c. The support arms 520 may be longer than the splines 510,as shown, to provide greater flexibility as compared to the splines 510,or alternatively, the support arms 520 may be generally the same orshorter than the splines 510. It will be appreciated by those skilled inthe art that the relative width and length of the splines 510 andsupport arms 520 may be easily determined to provide a desired extentand ease of expansion and collapse.

Optionally, as shown in FIG. 15D, the free ends 510 c of the splines 510may be treated to create tissue engaging elements, such as jagged tines513. Alternatively or in addition, the free ends 510 c may be bent orcurved, e.g., radially outward (not shown), to enhance engagement withbone or other tissue during implantation. In addition, one or morenotches 612 may be formed in a first end 520 a of each of the supportarms 520 to define tabs 614 for securing the support arms 520 to thecollar 512 (not shown). In a further alternative, the splines 510 andsupport aims 520 may be formed on a separate tubular sleeve that may beattached to one or both ends of a tubular shaft (not shown), e.g., bywelding, friction fit, mating threads, bonding, and the like.

Returning to FIGS. 14A and 14B, once the splines 510 and support arms520 are formed on or attached to one or both ends 504, 506 of thetubular shaft 502, collar(s) 512 may be inserted into the lumen 507 andthe first ends 520 a of the support arms 520 may be attached torespective collar(s) 512. The collar(s) 512 may include slots orrecesses (not shown) for receiving the tabs 614 of respective supportarms 520. In addition or alternatively, the first ends 520 a of thesupport arms 520 may be bonded or welded to the collar(s) 512.

Preferably, collar(s) 512 may be threaded over the control member 522into the tubular shaft 502. The control member 522 may be inserted intothe lumen 507 of the tubular shaft 502, and threaded through the annularregion 530 until the proximal and distal ends 524, 526 are disposedwithin the proximal and distal ends 504, 506 of the tubular shaft 506.The collar(s) 512 may be threaded onto proximal end 524 (and/or thedistal end 526) until the collar(s) 512 enter(s) the lumen 507 andbecome disposed proximate the first ends 520 a of the support arms 520.The support arms 520 may then be attached to the collar(s) 512, asdescribed above.

Initially, the device 500 may be provided such that the splines 510 arein their collapsed state, as shown in FIG. 13A. In the collapsed state,the splines 510 and support arms 520 may be disposed adjacent oneanother such that they extend substantially parallel to the longitudinalaxis 508. To expand the splines 510, a tool (not shown) may be used torotate the control member 522 in a predetermined direction. For example,as shown in FIGS. 14A and 14B, a slot 534 or other keyed element, suchas a lug (not shown) extending from the control member 522, may beprovided that may be engaged with the tool. Because the thread patternon the proximal and distal threaded regions 528 a, 528 c are oppositehand from one another, as the control member 522 is rotated, bothcollars 512 move outwardly from the lumen 507. Stated differently, theproximal collar 512 a moves proximally, while the distal collar 512 bmoves distally.

This action of the collars 512 causes the first ends 520 a of thesupport arms 520 to move axially outward (i.e., proximally for thesupport arms 520 on the proximal end 504). Thus, if splines 510 areprovided on both the proximal and distal ends 504, 506 of the tubularshaft 502, the first ends 520 a of the proximal and distal support arms520 may away from one another. Because the second ends 520 c of thesupport arms 520 are coupled to the splines 510, this causesintermediate regions 520 b of the support arms 520 to buckle and directsthe splines 510 radially outward until they are oriented substantiallytransversely with respect to the longitudinal axis 508 to define theexpanded state, as shown in FIG. 12.

Use of the device 500 to treat a fracture within a bone may proceedsimilar to the embodiments described above. The device 500 may beinserted through a previously formed entry portal into a medullary canalof a bone, such as the femur (not shown) with the splines 510 collapsed,as shown in FIG. 13A. Preferably, a guidewire or other element (notshown) is first introduced through the entry portal into the medullarycanal of the bone using conventional methods and extended to a distalsegment of the bone. The device 500 may then be advanced over theguidewire into the medullary canal, e.g., by inserted the guidewirethrough a lumen in the control member 522. After insertion of the device500, the guidewire may then be removed.

Once the device 500 is fully inserted within the medullary canal, thecontrol member 522 may be rotated to expand the splines 510 to theexpanded state, as shown in FIG. 13B. Preferably, the splines 510 areexpanded such that they substantially engage internal bone or othertissue, thereby substantially anchoring the device 500 relative to thebone. Thus, the device 500 may prevent segments of bone within which thedevice 500 is implanted from moving axially, bending, and/or rotatingrelative to one another. Optionally, if additional stability is desired,a proximal extension (not shown) may be provided that extends proximallybeyond the splines 510 on the proximal end 504. For example, the tubularshaft 502 may include an axial extension (not shown) that extendsproximally beyond the splines 510 (which may require elimination of oneor more of the splines 510 to accommodate the extension), oralternatively the control member 522 may extend proximally beyond thesplines 510. A plurality of holes (not shown) may be provided throughthe proximal extension, and screws, nails, or other fixation devices maybe inserted through the holes, e.g., transversely through the bone andthe proximal extension, to further secure the segments of bone.

An advantage of the threading of the control member 522 is that itallows the splines 510 on one end of the device 500 to be expanded to agreater size than the splines 510 on the other end. Rather than merelyrotating the control member 522, which may cause each set of splines 510to expand substantially equally to one another, an axial force may beapplied to the control member 522, causing the control member 522 tomove axially through the tubular shaft 502. Thus, rather than thecollars 512 moving relative to the tubular shaft 502, one collar 512 mayremain substantially stationary, while the other collar 512 movesfurther outwardly.

After the fracture has healed, the device 500 may be removed, similar tothe embodiments described above. During such removal, a tool may beintroduced to direct the splines 510 back to the collapsed state,similar to the method for expanding the splines 510. In furtheralternatives, the device 500 may include an indicator element (notshown) to facilitate location and/or removal of the device 500.

Turning to FIG. 16, an alternative embodiment of an intramedullarydevice 700 is shown that includes a first set of splines 710 on one end704 of a tubular shaft 702, similar to the previously describedembodiment. In addition, the device 700 includes a second set of splines740 that are located at an intermediate location between the ends 704,706 of the tubular shaft 702. The second set of splines 740 includessupport arms 750, both of which may be formed directly in a wall of thetubular shaft 702, similar to those formed on the end 704. A collar (notshown) may be inserted into the tubular shaft 702, e.g., threaded over arod or other control member (also not shown), similar to the previousembodiment until the collar is proximate the second set of splines 740.The support arms 750 may then be coupled to the collar, such thatrotation of the rod may cause the collar to move axially and expand thesecond set of splines 740, similar to the previously describedembodiment. Optionally, a plurality of holes (not shown) may be providedthrough the tubular shaft 702. Screws, nails, or other fixation devicesmay be inserted through the holes, e.g., transversely through the boneand the shaft, to further secure the segments of bone, similar to theembodiment described above.

Although only one set of intermediate splines 740 is shown, it will beappreciated that any number of sets of splines may be provided along thetubular shaft in a similar manner. Thus, when the device 700 isimplanted within a long bone, the device 700 may be expanded to engageseveral locations of the bone along its length. In addition, althoughthe first and second sets of splines 710, 740 are shown as havingsubstantially the same length, it will be appreciated that differentlength splines may be provided. For example, the intermediate set ofsplines may be made shorter than those on the end(s), e.g., to allowexpansion within a narrow region of a bone, while the set(s) of splineson the end(s) may expand within an enlarged region, e.g., end(s) of thebone.

In a further alternative, the devices in accordance with the presentinvention may be used as a base for an intramedullary primary fixationstem prosthetic section. For example, an adapter (not shown) may beattached to the device, e.g., to the tubular shaft proximal or distal tothe set of splines to which a prosthetic artificial joint surface, e.g.,a rounded component, socket or other joint element (also not shown), maybe attached. Alternatively, a prosthesis may be secured directly overthe set of splines. Thus, the devices may be used in joint replacementprocedures in addition to or instead of merely stabilizing a fracturedbone.

While preferred methods and embodiments have been shown and described,it will be apparent to one of ordinary skill in the art that numerousalterations may be made without departing from the spirit or scope ofthe invention. Therefore, the invention is not to be limited except inaccordance with the following claims.

1. A device for stabilizing bone comprising: (a) a tubular body that defines a longitudinal axis, said tubular body including: (i) a first tubular body region, (ii) a second tubular body region, and (iii) a spline region extending between the first tubular body region and the second tubular body region, and (b) an elongate control member disposed within the tubular body, the elongate control member: (i) having a substantially uniform diameter; and (ii) being non-threadably coupled with respect to the second tubular body region; wherein the spline region includes a plurality of splines movable between a collapsed state and an expanded state, each spline of said plurality of splines defining (i) a first spline end region coupled to the first tubular body region; (ii) a second spline end region coupled to the second tubular body region; and (iii) an intermediate spline region; wherein the spline region is substantially linear and substantially aligned with the longitudinal axis of the tubular body when the plurality of splines are in the collapsed state; wherein the spline region in the collapsed state has a substantially uniform diameter; and wherein non-rotational, linear axial movement of the control member within the tubular body towards the first tubular body region causes the second tubular body region to be displaced axially linearly towards the first tubular body region, thereby causing each of the intermediate regions of the plurality of splines to buckle outwardly relative to the longitudinal axis of the tubular body to define the expanded state; wherein non-rotational, linear axial movement of the control member within the tubular body away from the first tubular body region causes the plurality of splines to move from the expanded state to the collapsed state; and wherein the control member is actuated within the tubular body by a user to axially move the control member within the tubular body.
 2. The device of claim 1, wherein each spline of the plurality of splines is integrally formed from the tubular body.
 3. The device of claim 1, wherein each spline of the plurality of splines further includes at least one scored or thinned region configured to provide a hinge when each spline buckles as the second tubular region is displaced axially towards the first tubular body region.
 4. The device of claim 1, wherein the elongate control member is a solid rod or a hollow tubular member.
 5. The device of claim 1, wherein each spline of the plurality of splines is formed by cuffing longitudinal slits in the tubular body.
 6. The device of claim 1, wherein the elongate control member is a control wire.
 7. The device of claim 1, wherein the elongate control member is pulled by a user to displace the second tubular body region.
 8. The device of claim 1, wherein a user inserts a tool into the tubular body to engage the control member and to move the control member axially.
 9. The device of claim 1, wherein the diameter of the second tubular body region is substantially the same as the diameter of the spline region in the collapsed state.
 10. The device of claim 1, wherein the second tubular body region has a substantially uniform diameter; and wherein the diameter of the second tubular body region is substantially the same as the diameter of the spline region in the collapsed state.
 11. The device of claim 1, wherein the first and second spline end regions are coupled to the first and second tubular body regions by hinged joints.
 12. The device of claim 1, wherein the spline region is a substantially porous interconnection structure.
 13. The device of claim 1, wherein the elongate control member disposed within the tubular body is removable.
 14. A device for stabilizing bone comprising: (a) a tubular body that defines a longitudinal axis, said tubular body including: (i) a first tubular body region, (ii) a second tubular body region, and (iii) a spline region extending between the first tubular body region and the second tubular body region, and (b) a removable elongate control member disposed within the tubular body, the elongate control member: (i) having a substantially uniform diameter; and (ii) being non-threadably coupled with respect to the second tubular body region; wherein the spline region includes a plurality of splines movable between a collapsed state and an expanded state, each spline of said plurality of splines defining (i) a first spline end region coupled to the first tubular body region; (ii) a second spline end region coupled to the second tubular body region; and (iii) an intermediate spline region; wherein the spline region is substantially aligned with the longitudinal axis of the tubular body when the plurality of splines are in the collapsed state; wherein the spline region in the collapsed state has a substantially uniform diameter; wherein the spline region is a substantially porous interconnection structure; and wherein non-rotational, linear axial movement of the control member within the tubular body towards the first tubular body region causes the second tubular body region to be displaced axially linearly towards the first tubular body region, thereby causing each of the intermediate regions of the plurality of splines to buckle outwardly relative to the longitudinal axis of the tubular body to define the expanded state; wherein non-rotational, linear axial movement of the control member within the tubular body away from the first tubular body region causes the plurality of splines to move from the expanded state to the collapsed state; and wherein the control member is actuated within the tubular body by a user to axially move the control member within the tubular body.
 15. The device of claim 14, wherein each spline of the plurality of splines is integrally formed from the tubular body.
 16. The device of claim 14, wherein the elongate control member is a solid rod or a hollow tubular member.
 17. The device of claim 14, wherein the elongate control member is pulled by a user to displace the second tubular body region.
 18. The device of claim 14, wherein the diameter of the second tubular body region is substantially the same as the diameter of the spline region in the collapsed state.
 19. The device of claim 14, wherein the second tubular body region has a substantially uniform diameter; and wherein the diameter of the second tubular body region is substantially the same as the diameter of the spline region in the collapsed state.
 20. The device of claim 14, wherein the first and second spline end regions are coupled to the first and second tubular body regions by hinged joints. 